Ok im 17 6 foot 3 and 320 pounds, I know im fat but thats not my question. I have 8 lb dum bells and I do about 50 lifts per arm a day, but it doesnt really hurt, or become sore from doing that. If I were to get some like 15-20 lbs probably not that much. Would doing a lot less be just as beneficial as doing more on the 8 lb dum bells or should I get say 15 pound weights and doing like 25 lifts or so.